No abstract

In this article, we report the synthesis of polymer-functionalized graphene composites as highly potent flame retardants. Functionalized polyaniline (PANI)- and polypyrrole (PPy)-supported graphene nanocomposites were synthesized by the reaction of graphene oxide, and monomers of the above-mentioned polymers, aniline and pyrrole, respectively, in the presence of phosphoric acid. These synthesized nanocomposites show excellent flame-retardant properties when coated with cotton fabric and wood. When G-fPANI and G-fPPy solutions were coated on a cloth piece which was exposed to a flame its initial shape and size were sustained by liberating a little amount of smoke. At the initial stage, the coated cloth did not catch fire for more than 620 s (10.20 min) and 380 s (6.20 min) in case of G-fPANI and G-fPPy, respectively, whereas the use of only PANI, PPy, and GO coated on blank cloths were totally burned within 14, 10, and 10 s, respectively. Blank cloth subjected to fire was totally burned within 10 s, leaving small amounts of black mass. Flame-retardant efficiency of G-fPANI- and G-fPPy-coated cloth was confirmed by detailed flame tests such as a limiting oxygen test (LOI), vertical flammability test, and exposure to high temperature (∼1500 °C). In the case of the LOI test, G-fPANI- and G-fPPy-coated cloths show high values up to 47.6 and 41.9 indicating an excellent flame-retardant property. Like cotton fiber, wood was also used to check the flame-retardant nature of prepared nanocomposites, and it showed good results. This is the first time such a novel approach has been made to prepare polymer-functionalized graphene nanocomposites as a flame retardant for fire prevention using a simple, cost-effective route in comparison to prior work.

We report a simple and green approach to develop the deep eutectic solvent functionalized graphene derivative as an effective flame retardant. The deep eutectic solvent functionalized graphene oxide (DESGO) was synthesized by introducing nitrogen-supported phosphorus functional groups on the surface of graphene derivative via a deep eutectic solvent, which is prepared by the treatment of monosodium dihydrogen orthophosphate and choline chloride. Subsequently, the resultant DESGO material is characterized by X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The as prepared DESGO solution coated cloth piece was sustaining its initial shape and size by releasing a little amount of smoke at the early stage without catching fire for more than 540 s (9 min), whereas the pristine cloth is totally burned out within 10 s, leaving small amounts of black mass. This simple method of directly functionalized deep eutectic solvent on a graphene oxide surface can be a common process for the cost-effective bulk production of a nano carbon template for extremely high potency, nontoxic flame retardant applications.

A green approach to the synthesis of sulfur and nitrogen co‐functionalized reduced graphene oxide (SN‐rGO) is presented; it involves the reduction of graphene oxide (GO) using a deep eutectic solvent (DES) as chemical reducing agent and dopant. For the first time, a DES of choline chloride and sodium sulfide comprising cheap and safe components is introduced, and is both highly effective and reusable as a reducing agent for the production of SN‐rGO. The DES is utilized as a solvent as well as reducing agent and dopant to generate SN‐rGO. This DES is highly efficient in removing oxygen functionalities from GO and for subsequent sulfur and nitrogen functionalization for high energy‐storage efficiency. The reduction ability of this DES is confirmed with five consecutive cycles, which adds to its sustainability and recyclability in the development of energy‐storage devices. SN‐rGO exhibits a high specific capacitance of 509 F g−1 at 1 A g−1, which corresponds to high energy and power densities of 57.3 Wh kg−1 and 1804.7 W kg−1, respectively. This simple and green method for direct reduction of GO with sulfur and nitrogen functionalization on the graphene surface can provide cost‐effective bulk production of a nanocarbon template for energy storage applications.

In this article, we have proposed a simple, environmentally benign and highly effective method for the reduction of graphene oxide (GO) by using carbonic acid as a chemical reducing agent to synthesize the reduced graphene oxide (rGO). Carbonic acid has been synthesized by mixing the dry ice (solid CO2) with deionized water and by the mixing of acetic acid and sodium bicarbonate. The formed carbonic acid utilized to remove the oxygen‐containing functionalities of GO to produce rGO. Surprisingly, the synthesized rGO has shown aqueous dispersible property, which helps to disperse rGO in water for a prolonged time. The electrochemical activity of resulting materials has been achieved by measuring specific capacitance by cyclic voltammetry (CV) and galvanostatic charge‐discharge (GCD). Specific capacitance of resultant material is 350.3 F g−1 at 1 A g−1 with good cyclic stability performance indicating supercapacitive nature of the resultant material. According to the data obtained, it is observed that as‐prepared carbonic acid is capable of producing carboxyl functionalized graphene which leads to disperse rGO in water. This preparative method will overcome the problems to prepare rGO dispersion in aqueous medium rather than in hazardous organic solvents.